Alyssa K. Betts, Extension Field Crops Pathologist; akoehler@udel.edu
Barley heading is getting close, and wheat is approaching flag leaf. We are currently at low risk across most of the state and medium risk along coastal Sussex in the Fusarium Risk Tool (Figure 1). The next few days are dry, but we will need to keep an eye on the rains forecasted for the end of next week. Barley starts flowering prior to heading, while wheat usually starts to flower after heading out. Look for yellow anthers in the center of the wheat head to signal the start of flowering (Figure 2). Weather can impact how many days from when heads become visible until flowering begins. Some years it may be 3-4 days while others I have waited 10-11 days. Once wheat is flowering, fungicides are most effective when applied within 4–5-days. For best mycotoxin (DON) control, it is better to be at flowering or a few days beyond, than to spray too early when heads are not out yet. Anthers can remain attached after flowering but become a pale white. Fungicide products should be applied at the manufacturers recommended rate with nozzles angled 30-45° from horizontal (30 degrees is better than 45). Nozzles angled both forward and backward or twinjet nozzles that spray in two directions give better contact with the head and increase fungicide efficacy. For ground sprays, fungicides should be applied in at least 10-15 gallons of water per acre; aerial applications are recommended at 5 gallons per acre.
Figure 1. FHB Risk Model for April 17, 2025 (wheatscab.psu.edu)
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Figure 2. Wheat at flowering (Feekes 10.5.1) with yellow anthers visible